1. Field of the Invention
The present invention relates to an electronic camera and signal amplification ratio adjusting method for the electronic camera in which a gain utilization area is restricted to an area in which mixed colors are indistinctive.
2. Description of the Related Art
In a video camera or an electronic camera, a white balance control is executed in such a manner that a white reproduced image can be obtained when a white subject is photographed. This is executed by performing gain adjustment with a red signal, a blue signal and a green signal of a CCD in a camera being determined as references.
Further, in an image integration type auto white balance circuit, control is effected based on information that achromatic colors are obtained when color signal components in an entire imaging screen are integrated. Specifically, a red integration value IR, a green integration value IG and a blue integration value IB are obtained by respectively integrating a red signal R, a green signal G and a blue signal B in accordance with each field, and a ratio IR/IG of the red integration value IR with respect to the green integration value IG and a ratio IB/IG of the blue integration value IB with respect to the green integration value IG are calculated.
Then, white-balance balance control signals Rcont and Bcont with which the following expression can be achieved are obtained.(IR/IG)=(IB/IG)=1Furthermore, the gain of the red signal R is adjusted in accordance with a value of the control signal Rcont, and the gain of the blue signal B is adjusted in accordance with a value of the control signal Bcont, thereby controlling the white balance.